VOL. XLVII.] PHILOSOPHICAL TRANSACTIONS. 26/ 



out at pleasure, to prevent the animal being taken when pursued : but this 

 liquor, according to our author, serves the animals, the subjects of this treatise, 

 with a matter capable of becoming hard ; and furnishes the increase of the body 

 or shell of the animal, which, like other shells, remains always of the same form, 

 and is of a size projx)rtionable to the animal. In the madrepora it lifts itself up 

 under the animal, which always lies upon it ; but in the millepora it increases 

 from the centre as the animal grows larger ; and thus these marine productions 

 grow in just proportions. 



These animals are nourished without changing their place, like American 

 oysters, which fasten themselves to the roots of the mangles ; or like what has 

 been heretofore called concha anatifera, which fastens itself to old planks. Na- 

 ture has furnished these polypes with claws, which they occasionally protrude 

 from their cells, and seize their prey, as it passes by them ; and thus they are 

 nourished and increase, according to their particular mechanism and construction. 



There are some species of the polype of the madrepora, which are produced 

 singly, others in clusters. The first of these kinds may arise from the parent 

 animal furnishing only one egg at a time: other species deposit a number of 

 these eggs at the same time ; which, coming to life altogether, are joined in 

 such a manner, that they seem to constitute one and the same body. 



The millepores grow one upon another ; their little animals produce their 

 spawn, which attaching itself either to the extremity of the body already formed, 

 or underneath it, gives a different form to this production. Hence the various 

 shapes of the millepora, which is composed of an infinite number of the celjs of 

 these little insects, which altogether exhibit different figures, though every par- 

 ticular cellule has its essential form, and the same dimensions, according to its 

 own species. 



On the whole, we see, that M. de Peyssonnel, if his system is admitted, has 

 made a great alteration in this part of natural history. Naturalists had been 

 divided, whether coral, and the harder productions of the sea, should be consi- 

 dered as plants or stones. Those who considered them as stones, among whom 

 was Dr. Woodward, imagined themselves justified in this opinion from their 

 excessive hardness, and from their specific gravity ; and they were confirmed in 

 this by observing, that if these bodies were calcined, they were converted into 

 lime. Guisonagus, in his letter to Boccone, says positively that coral is not a 

 plant, but a real mineral, composed of much salt and a small quantity of earth : 

 he supposes its form given it by a precipitation, something like that of the arbor 

 Dianae of the chemists. 



Dioscorides, Pliny, Caesalpinus, Boccone, Ray, Tournefort, and Geof^roy, 

 thought coral to be a plant, from its root being fixed to rocks or stones, as those 

 of trees are to the earth ; and from its sending forth a trunk, which ramified into 



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